textproduct: Rapid City

KEY MESSAGES

- Areas of dense fog return tonight into Saturday morning.

- Mild and mostly dry this weekend

- Rain and gusty northwest winds Monday into Monday night; some light snow possible over the higher Black Hills.

DISCUSSION

(This Evening Through Friday) Issued at 123 PM MDT Fri Oct 30 2026

A slow-moving deep upper trough is sitting just offshore the Pac NW. Southwesterly flow is stretching across most of the western CONUS into the northern Plains. WV imagery shows a strong shortwave crossing the Great Basin into WY. Surface obs show S/SE winds continuing with temps in the 40s to lower 50s at this time. Temps are struggling to warm across NW SD where low clouds/fog has lingered. Webcams show visibility has improved quite a bit but some fog is lingering especially across higher ridges and buttes. Low clouds will persist tonight with fog/drizzle expected to redevelop and expand across large portions of the western SD plains up to the foothills of the Black Hills...and even stretch back into portions of the NE WY plains. The fog will likely be dense again over some areas through Saturday morning. Dense Fog Advisories may be needed again. Weak ridging ahead of the incoming shortwave will bring some warm air advection in tonight into Saturday. Highs in the 60s to near 70 are expected, but if low clouds/fog end up lingering longer than expected across the western SD plains, this could keep temps cooler than forecast. Generally dry weather is expected Saturday, though could see isolated showers across south central SD late Sat as the shortwave crosses the region. The Pacific trough/low will finally make its way across the western CONUS through Sunday. Surface low pressure will develop across eastern WY through the CO Front Range. Southerly return flow will increase ahead of the low across the Neb/SD plains. Highs on Sunday will be in the 60s, but then cooler weather is expected Monday as colder air is ushered in on the backside of the low as it crosses the northern/central Plains. Strong forcing with this system will bring extensive rainfall to the region, but models at this time show most of that rain falling across East River SD. However, rain is still expected across the CWA...though lower amounts. The exception may be the northern Black Hills where upslope enhancement could bring higher totals. There still remains much uncertainty as to how much QPF the area might see. Gusty NW winds are also expected Monday into Monday night, but again, there is disagreement as to how strong these winds might be. Another variable to consider is how much snow the higher Black Hills might see. This system is quite warm, but light accumulations are possible across the highest terrain, depending on how much precip remains as colder air arrives. It's another aspect of the storm we'll be watching through the weekend.

AVIATION

(For the 18Z TAFS Through 18Z Saturday) Issued At 1115 AM MDT Fri Oct 30 2026

Fog will continue to burn off across northwestern SD. A low cloud deck will remain in place for most of western SD through the day, as well as portions of northeast WY excluding KGCC. Conditions will remain mostly unchanged going into tonight. Fog is expected to develop over parts of western SD Saturday, bringing LIFR conditions. Clouds decks will drop after about 03Z, followed by visibilities 1-2 hrs later. These conditions are expected to stay in western SD, however WY may see cloud bases drop to near MVFR cigs. For now, have left out low clouds from KGCC but will update pending future model guidance.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.